34. Jaqen H'ghar
Technically, "a man has no name" – but for the purposes of this list "Jaqen H'ghar" will have to do. As a member of the mystical order of assassins known as the Faceless Men, he may well be the single deadliest person we've encountered on the show, which is really saying something. He helped Arya Stark escape captivity and trained her in his lethal ways – then let her go free when he saw she could learn no more from him because her love for her family was still too strong. Faceless? Yes. Heartless? Definitely not.